Partially gelatinized corn and potato starch show faster digestibility after retrogradation

Starch digestibility is determined by a coordination of gelatinization and retrogradation during food preparation, while the impact of partial gelatinization and continuous retrogradation on starch digestibility remains unclear. Therefore, corn and potato starch were gelatinized at various degrees, followed by retrogradation. Distinct from fully gelatinized starch, some partially gelatinized starches showed faster digestion rates after retrogradation. Notably, digestion ratio of corn starch pre-gelatinized for 20 s increased by 17.7 % at 120 min after retrogradation. Furthermore, partially gelatinized corn starch sticked together, while potato starch showed a clearer granule-by-granule gelatinization pattern. Both partially gelatinized corn and potato starch showed a decreased short-range ordering after retrogradation. Amylose chains with 80 glucose units in corn starch, while amylopectin chains with 13 glucose units in potato starch were more resistant to digestion. Collectively, these findings indicate that retrogradation does not necessarily decrease starch digestibility, as it also depends on the degree of gelatinization.